Ball and socket joints of the type mentioned in the introduction are used, for example, but by no means exclusively, at the chassis or at the wheel suspension of motor vehicles, e.g., as a support joint or as a guiding joint. Ball and socket joints of this class comprise a sensor device, with which forces and loads acting on the ball and socket joint can be determined or measured.
Ball and socket joints of the type mentioned in the introduction with means for measuring forces and loads are used, for example, on the motor vehicle in order to make it possible to reliably determine there the forces or bending moments acting on the ball and socket joint during the real driving operation or even during testing operation on the test bench. Such measurements of forces on ball and socket joints in the area of the chassis of a motor vehicle make it possible to infer the dynamic state of a motor vehicle. It is thus possible to achieve, in particular, an improvement of the data base for driving safety systems, for example, ESP or ABS. Ball and socket joints of this class are thus used, among other things, to improve the driving safety of the motor vehicle.
A ball and socket joint with force sensor device is known, for example, from DE 101 07 279 A1. The ball and socket joint known from this document is used especially to determine or analyze the force acting in a certain component of a motor vehicle, for example, the axial force present in a tie rod because of forces of reaction from the chassis. According to the teaching of this document, provisions are made for this, among other things, for providing a ball and socket joint arranged between different components of the steering linkage with wire strain gauges or piezo pressure pick-ups in the area of the ball pivot and to infer the load on the ball and socket joint and hence the axial forces acting in the steering linkage on the basis of the signals of these sensors.
However, the equipping of ball and socket joints with such wire strain gauges or piezo sensors is associated with a rather substantial effort. At first, a corresponding surface must be created for arranging these components, mostly at the ball pivot, to which, for example, the wire strain gauge must then be bonded. In addition, an electric wire connection must also be established to a separate electronic analysis unit, and the electronic analysis unit must be arranged, in addition, at a suitable site in a protected manner. On the whole, this leads to a complicated and hence expensive manufacture of such ball and socket joints provided with load sensors, and, moreover, the exposed sensor system and wiring of such ball and socket joints are sensitive and therefore threatened by failures.
In addition, it is hardly possible in the prior-art ball and socket joints with force sensor device to derive additional information on the state especially of the ball and socket joint by means of the force sensor device beyond the load situation proper of the ball and socket joint. However, since ball and socket joints arranged in the area of the chassis or the steering of motor vehicles are safety-relevant components, whose failure may lead to fatal consequences especially during driving, it is especially desirable to make it also possible to permanently obtain information on the instantaneous operating state or state of wear of the ball and socket joint.